Pre-infiltrative lesions of ground glass nodules are mostly not important and close follow-up is sufficient. Pre-infiltrative lung lesions, also known as glandular precursor lesions, mainly include adenocarcinoma in situ and atypical adenomatoid hyperplasia. Atypical adenomatous hyperplasia refers to the atypical proliferation of alveolar wall cells, and carcinoma in situ refers to the atypical proliferation of cells involving the entire lung epithelium without breaking through the epithelial basement membrane. Atypical adenomatoid hyperplasia and adenocarcinoma in situ are precancerous lesions of invasive adenocarcinoma and alveolar carcinoma of the lung. Carcinoma in situ has been excluded from the classification of malignant neoplasms in the latest classification of the World Health Organization (WHO) 2021, and together with atypical adenomatoid hyperplasia, are not included in the category of lung malignancies. The biological behavior of atypical adenomatous hyperplasia and adenocarcinoma in situ is considered to be similar to that of benign tumors, but because of the risk of malignant transformation, they should be closely followed up and observed, and if they progress to invasive adenocarcinomas, they should be treated in a timely manner. Patients are advised to consult their specialists and follow the medical advice for follow-up and treatment.